Democratic senator Claire McCaskill will be leading an investigation into the manufacturers of the nation’s top 5 prescription opioid products, according to a press release by the Homeland Security & Governmental Affairs committee.

The inquiry will look into the practices of Purdue, Janssen/Johnson & Johnson, Insys, Mylan, and Depomed.

As part of the investigation, which the press release characterised as “wide-ranging,” the committee is asking the corporations to provide data about sales, marketing materials, internal addiction studies, details on compliance with government settlements, and donations to third party advocacy groups.

The press release states the investigation’s mission is to “explore whether pharmaceutical manufacturers … have contributed to opioid over-utilization and overprescription.”

McCaskill’s investigation comes as the country is struggling to cope with a growing drug epidemic that’s sweeping its suburbs, while researchers are uncovering more links between prescription opioid marketing and deaths from drug overdose.

A report by the Associated Press, for example, found that the makers of opioid painkillers outspent the gun lobby on campaign contributions and government lobbying by a ratio of 8 to 1. Purdue Pharmaceuticals, one of the subjects of McCaskill’s investigation and the maker of OxyContin, spent nearly $US1 billion in lobbying from 2006 to 2015, which included efforts to support drugs.

The report also found that in 2015 alone, 227 million prescriptions for opioids were given out, which was “enough to hand a bottle of pills to nine out of every 10 American adults.” That year, 52,404 people died from drug overdoses, according to the Centres for Disease Control and Prevention.

Addressing the epidemic, McCaskill said, “All of this didn’t happen overnight — it happened one prescription and marketing program at a time.”

She added: “The vast majority of the employees, executives, sales representatives, scientists, and doctors involved with this industry are good people and responsible actors, but some are not. This investigation is about finding out whether the same practices that led to this epidemic still continue today, and if decisions are being made that harm public health.”